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Surging Cycling water pressure

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 Soooooooo I had an older Flo Jet fresh water pump and one of those pressure accumulator tanks that allowed for smooth even no short cycling pressure at the faucets....(worked great smooth even pressure no short cycling) The old pump was failing so I just replaced it with a Shur Flo 4008 -101-A65  55 PSI Pump (dont know the kick in pressure)  and made NO changes to the pressure accumulator left it in the circuit.......AFTER the new pump was installed it started the classic short cycling surging with NO smooth regulation like before.....I let water drain and had pump on n off etc but it didnt help......I had water off, no pressure, let the air out of the tank, recharged to 30 PSI (figured it needs below the kick in PSI but dont know what that is)  NOW THE SHORT CYCLING AND SURGING IS MUCH WORSE  grrrrrrrrrrrr

 With such small volume its hard to tell if the air bladder tank is holding but Im pretty sure its holding at 30 PSI BUT NOW SHORT CYCLING IS TERRIBLE 

 Ideas ?? hints ?? welcome THANKS YALL

John T NOTTTTTTTT a plumber grrrrrrrrrrr



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39 minutes ago, Darryl&Rita said:

Agree with Vern. Or did you close the tank isolation valve while working on the pump plumbing? Remember to open the valve? Don't ask me how I know this issue.

I didnt close anything I just turned the pump off (and hose city water was off of course) and when I removed the hose on the pressure OUTPUT (accumulator tank input) side of the old pump there was a lot of water under a lot of pressure until it all drained  out,,,,,,,,,then I installed new pump (did NOT mess with tank or bladder air pressure or anything) AND SHORT CYCLING SURGING TOOK PLACE and after I drained air pressure and re charged to 30 PSI now its worse gggggrrrrrrrrrrrrrrrr


 Im going right now and drain the air tank and refill to 20 PSI see what happens??


PS I let air out charged t0O20 NO CHANGE NO HELP


 i LET ALL AIR OUT   no change no help still cycles and surges


 Air tank went abd in process of change need new tank """????/


John T  

Edited by oldjohnt
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   If you drain your supply hose  from the hydrant, then hook it back up. Then turn the water on. Next is to go inside and run the hot water only, it will put a air charge in your hot water tank. The excess air will come out of the hot faucet.

   That will provide a air cushion in the water system.


   The on/off pressure switch on your new pump may be adjusted so the on and off setting is too close. Although I never look at how to adjust one. A person could install a water system pressure switch like on a Well system.

   Many years ago I did that on a older RV.


 It is frustrating when simple things go into the unknown pain in the rear attitude department.

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It's sort of acting like the accumulator isn't there. I see you said it's holding pressure. Is that when it's connected to the water line or just by itself, no pipe connected? If it's not holding pressure just by itself, the tank is bad.

I wonder if the reading you're seeing is the "system" pressure and not the bladder pressure.

I have a small expansion tank from Lowes installed, it's rated up to 60psi.  The rig is in winter hibernation so I can't check what it's charged to, but I'm certain its more than 30 psi.


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   If I remember correctly, you normally have 2 lbs less pressure than what the system cut in pressure is.

   If it is over it, the switch should not turn the pump on. Until the pressure drops in the water line. I believe that would give unstable pressure in the system.


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PROBLEM SOLVED:  My bad (Not familiar with borrowed compressor and its air chuck) 

 I had borrowed a friends Milwaukee 20 V Lithium Digital Compressor (never seen or used it before) to air up the accumulator tank..You set the pressure to 30 PSI,,,,,,,,,,, Push the air chuck onto the tanks air bladder charge inlet,,,,,,,,,,You hear it make a seal, compressor loads down and it shuts off at 30 PSI                                                                           SOUNDS REASONABLE 

 Buddy comes over says you need to thread the chuck on NOT just push n hold although it sounds like it seals and pumps air until 30 and shuts off           NOT

 I thread it full on, set to 30, pumps up to 30 and shuts off same as before HOWEVER as I fast as I can unscrew the chuck and hear air leaking DUE TO SUCH SMALL VOLUME OF BLADDER air pressure dropped down to 10 by the time it stopped.  Sooooo I experimented a few times airing and unscrewing and reading digital gauge at end to see the pressure lost in process,,,,,,,,,Air it up to 50 PSI,,,,,unscrew chuck and at end its around 30 PSI,,,,,,,Pumps cut in pressure is around 30 to 35,(55 is cut off) 


  Moral of the story READ DIRECTIONS on something you're unfamiliar with (NOT my best practice lol) and never used before. That air bladder is so small even the slightest leak when disconnecting (removed as fast as possible) drops the internal air pressure Grrrrrrrrrrr  Anyone here never made a mistake lol  NOT ME and I admit it WELL DRATS

 John T  Live in RV at Florida Flywheelers Fort Mead Florida now with good steady fresh water tank n pump pressure  ONE HAPPY CAMPER          Thanks everyone

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11 hours ago, RV_ said:

Thanks for the rest of the story too John.

Youre welcome I enjoy feedback and hearing what happened when a problem is posted here including mistakes grrrrrrrrrrrr lol

 John T Florida Flywheelers Fort Meade Florida

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5 hours ago, oldjohnt said:

Youre welcome I enjoy feedback and hearing what happened when a problem is posted here including mistakes grrrrrrrrrrrr lol

 John T Florida Flywheelers Fort Meade Florida

Me two!

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